INHIBITION OF MURINE SARCOMA CELL ADHERENCE TO POLYSTYRENE SUBSTRATA BY BACILLUS-CALMETTE-GUERIN - EVIDENCE FOR FIBRONECTIN-MEDIATED DIRECTANTITUMOR-ACTIVITY OF BCG

Bacillus Calmette-Guerin (BCG) inhibited adherence of S180 mouse sarco ma cells and WI38 human diploid fibroblasts to the polystyrene substra tum of 24-well cluster dishes in a dose-dependent manner. This propert y was retained by washed or heat-killed bacilli, but not by the vaccin e filtrate or by the spent bacterial culture medium. Adhesion of bacil li to nonadherent S180 cells was demonstrated by light and scanning el ectron microscopy, but was not seen after trypsinization of adherent c ells, indicating that bacilli bind to cell-surface adhesins. Preincuba tion of bacilli with human fibronectin abolished their ability to inhi bit S180 adherence, suggesting that the phenomenon may be mediated by interaction of bacilli with cell-surface fibronectin. Fibronectin pret reatment of the bacteria also decreased their inhibition of S180 tumor growth in vivo, indicating that this mechanism may be at least partly responsible for BCG vaccine's observed antineoplastic activity.